Technical Field of the Invention
The present invention relates to a stator of a rotary electric machine that is installed in a vehicle and used as an electric motor or a generator, relates to a rotary electric machine provided with the stator, and relates to a method of manufacturing the stator.
Related Art
Well-known stators for rotary electric machines include a stator core and a stator winding. The stator core is provided with a plurality of slots arrayed in the circumferential direction. The stator winding, with conductors thereof being accommodated in each slot and electrically connected to each other, is wound about the stator core. A patent document JP-A-2010-226861, for example, discloses a stator winding which is formed of conductors (flat wires) each having a rectangular cross section perpendicular to the longitudinal direction.
With the activation of such a rotary electric machine, current passes through the stator winding. Accordingly, the conductors, which form the stator winding, generate heat on the basis of their electric resistance and thereby raise the temperature. In this case, when the stator winding is formed of flat wires as in the patent document JP-A-2010-226861, the conductors will have a high space factor in each slot. Therefore, compared to the case where a stator winding is formed of conductors each having a circular cross section perpendicular to the longitudinal direction (round wires), the flat wires will have a low resistance and hence will have a low copper loss to thereby minimize heat generation. On the other hand, however, use of flat wires raises a problem of not easily allowing passage of refrigerant, such as air or cooling oil, through each slot because the conductors are arrayed in the slot with almost no gap therebetween. This raises a problem of inefficient radiation performance.